1. Technical Field
The present invention relates to a liquid feed valve unit and a liquid ejection device.
2. Related Art
Inkjet printing devices (hereinafter referred to as “printing devices”), for example, and the like are known as liquid ejection devices for ejecting a liquid. A printing device is a device for recording characters, images, and the like on a recording medium. A printing device is configured so that ink is ejected to a recording medium from a nozzle provided to an ejection head. The ejection head is mounted to a carriage, for example, or other movement mechanism, and is configured so as to eject ink while moving over the recording medium.
In a printing device of the type referred to as “off carriage,” an ink cartridge is disposed on the case side of the device, and ink is fed to an ejection head via a feed tube from the ink cartridge. Such a printing device has an ink feed valve unit on the carriage side, and the ink feed valve unit has self-sealing functionality (see Japanese Laid-Open Patent Publication No. 2009-178889, for example).
The ink feed valve unit is provided with an ink feed chamber and a pressure chamber. The ink fed from the ink cartridge is fed to the ejection head through the pressure chamber from the ink feed chamber. A movable valve is provided between the ink feed chamber and the pressure chamber, and the ink feed chamber and the pressure chamber are communicated and non-communicated by the opening and closing of the movable valve. The ink feed valve unit is configured so that a reduction in the amount of ink inside the pressure chamber causes a film member which constitutes a portion of the pressure chamber to change position, and this position change is directly transmitted to the movable valve, thereby operating the movable valve. A configuration has recently been adopted in which a plate-shaped pressure-receiving part is attached to the center part of the film member, the pressure-receiving part is pushed toward the pressure chamber to push the movable valve, and the movable valve is thereby opened.
When ink is consumed by the ejection head, the amount of ink in the pressure chamber decreases and the pressure of the pressure chamber decreases. The movable valve opens when the pressure of the pressure chamber decreases, and ink is fed to the pressure chamber from the ink feed chamber. An amount of ink corresponding to the amount of ink consumed in the ejection head is fed to the pressure chamber. Pressure upstream from the ink feed valve unit therefore does not affect the ejection head side.